To the ego, the present moment hardly exists. Only past and future are considered important. This total reversal of the truth accounts for the fact that in the ego mode the mind is so dysfunctional. It is always concerned with keeping the past alive, because without it - who are you?

The most common ego identifications have to do with possessions, the work you do, social status and recognition, knowledge and education, physical appearance, special abilities, relationships, person and family history, belief systems, and often also political, nationalistic, racial, religious, and other collective identifications.

None of these is you.

Eckhart Tolle

Source: The Power of Now : A Guide to Spiritual Enlightenment, Pages: 37

When you are present, you can allow the mind to be as it is without getting entangled in it. The mind in itself is a wonderful tool. Dysfunction sets in when you seek your self in it and mistake it for who you are.

Eckhart Tolle

Source: The Power of Now : A Guide to Spiritual Enlightenment, Pages: 40

The pain that you create now is always some form of nonacceptance, some form of unconscious resistance to what is. On the level of thought, the resistance is some form of judgment. On the emotional level, it is some form of negativity. The intensity of the pain depends on the degree of resistance to the present moment, and this in turn depends on how strongly you are identified with your mind.

Eckhart Tolle

Source: The Power of Now : A Guide to Spiritual Enlightenment, Pages: 27